海鲜养殖对环境的影响较小

One of the best ways to reduce our impact on the environment is by changing what we eat. Researches show us that we can have the biggest impact by eating less meat and dairy or substituting lower-impact meats such as chicken and pork for beef and lamb. But I’m often asked the question： “What about fish and seafood？ Is that an environmentally-friendly option？”

“Environmental impact” can mean very different things： greenhouse gas emissions， land use， water use or chemical pollution. It’s useful to look at all of these impacts in case there are large trade-offs between them.

In a new study published in Nature， Jessica Gephart and colleagues conducted a meta-analysis of the impacts of fish and seafood across multiple environmental metrics（指标）. To do this， they combined life-cycle analysis data from studies of wild-caught and farmed seafood products. It covered over 1690 fish farms and 1000 records from fisheries.

Here， we’re looking at five key metrics： greenhouse gas emissions， land use， freshwater use， and nitrogen（氮） and phosphorus（磷） pollution. Comparing fish to other types of fish is useful. But we also want to know how seafood compares to other protein foods. So， we’ve included chicken for comparison. Chicken tends to have the lowest environmental impact of meat and dairy products – much less than beef and lamb and a bit better than pork. So when we make this comparison， we’re really seeing how seafood compares to animal protein with the lowest impact.

Overall， we see that a lot of seafood has a relatively low environmental impact compared to animal protein sources. Many types have a lower carbon footprint than chicken （those that are higher are around 20-30% higher）. Most farmed seafood needs less land and freshwater and causes less nitrogen and phosphorus pollution. This is because fish tend to be more efficient than chickens in converting feed into meat， which means they need less feed per kilogram.

（材料选自Our World in Data网站，有删改）

1. What is the purpose of the question in the first paragraph？

A. To highlight the benefits of beef.

B. To support the consumption of pork.

C. To emphasize the importance of meat.

D. To introduce the topic about seafood.

2. Which of the following is true about the new study？

A. It was carried out by Jessica Gephart.

B. It was published in various magazines.

C. It involved a large number of fish farms.

D. It highlighted wild-caught seafood products.

3. How does the author analyze the environmental impact according to paragraph 4？

A. By making comparison.

B. By listing data.

C. By explaining the concept.

D. By giving an illustration.

4. Why do fish have a lower carbon footprint than chicken？

A. They need lower levels of protein sources.

B. They require less food to generate meat.

C. They lead to lighter pollution.

D. They cut the use of water.

1.D。解析：推理判断题。材料第一段的最后一句提到“但我经常被问到这样一个问题：鱼和海鲜怎么样？这是一个环保的选择吗？”下文则主要介绍一些对比研究，得出海鲜养殖对环境影响的结论，因此该问题的写作意图是引出话题，故选D。

2.C。解析：细节理解题。材料第三段的最后一句提到“它覆盖了1690多个养鱼场和1000份渔业记录”，由此可知该研究涉及了大量的渔场，故选C。

3.A。解析：写作手法题。第四段的最后一句提到“所以当我们进行这个比较时，我们真正看到的是海鲜与动物蛋白相比，对环境的影响是最低的”，由此可知使用的是对比的写作手法，故选A。

4.B。解析：推理判断题。材料最后一段的最后两句提到“大多数海鲜养殖需要更少的土地和淡水，造成的氮磷污染也更少。这是因为在将饲料转化为肉类方面，鱼往往比鸡更有效，这意味着它们每公斤需要的饲料更少”，B选项与材料内容相符，故选B。